As is known, sensing elements are used in a variety of applications. Sensing elements include, but are not limited to, pressure sensing elements, temperature sensing elements, light sensing elements, acoustic sensing elements and magnetic field sensing elements. Magnetic field sensors, for example, are circuits generally including one or more magnetic field sensing elements, generally in combination with other circuits. In one application, a magnetic field sensor can be used to detect a direction of a magnetic field. In another application, a magnetic field sensor can be used to sense an electrical current. One such magnetic field sensor is described in U.S. Pat. No. 8,350,563 entitled “Magnetic Field Sensor and Method used in a Magnetic Field Sensor that Adjusts a Sensitivity and/or Offset over Temperature,” which is assigned to the assignee of the present disclosure and is incorporated herein by reference in its entirety.
Various parameters characterize the performance of magnetic field sensors and their magnetic field sensing elements. These parameters can include sensitivity, which is a change in an output signal of a magnetic field sensing element in response to a change of magnetic field experienced by the magnetic field sensing element, and linearity, which is a measure of how a magnetic field sensing element output signal varies in direct proportion to a magnetic field. Another parameter used to characterize a magnetic field sensor is an offset value (or more simply “offset”). Offset is a measure of how far removed from zero a magnetic field sensing element output signal is when the magnetic field sensing element experiences a zero magnetic field.
While it is desirable to limit an amount of current flowing into magnetic field sensors and similar circuits (e.g., for power usage considerations), a competing requirement is that magnetic field sensor performance (e.g., signal-to-noise ratio (SNR)) tends to improve when providing magnetic field sensing elements with more current. Magnetic field sensing elements tend to have sensitivities to magnetic fields (i.e., output voltages per Gauss) directly related to a magnitude of a current with which they are powered or driven. Additionally, an improved (or higher) SNR typically provides better performance on magnetic field sensor specifications that require consistent switching locations, including jitter (also sometimes referred to as repeatability).